A circular cross-section PDMS microfluidics system for replication of cardiovascular flow conditions.

Since the inception of soft lithography, microfluidic devices for cardiovascular research have been fabricated easily and cost-effectively using the soft lithography method. The drawback of this method was the fabrication of microchannels with rectangular cross-sections, which did not replicate the circular cross-sections of blood vessels. This article presents a novel, straightforward approach for the fabrication of microchannels with circular cross-sections in poly(dimethylsiloxane) (PDMS), using soft lithography. The method exploits the polymerization of the liquid silicone oligomer around a gas stream when both of them are coaxially introduced in the microchannel with a rectangular cross-section. We demonstrate (i) the ability to control the diameter of circular cross-sections of microchannels from ca. 40-100 mum; (ii) the fabrication of microchannels with constrictions, and (iii) the capability to grow endothelial cells on the inner surface of the microchannels.

Entrapment of a subclavian venous catheter in a child--how to get it out?

OBJECTIVE: To report a rare case of an entrapped subclavian venous catheter and to describe an anatomically based maneuver to remove it. DESIGN: Case report. SETTING: Pediatric critical care unit in a tertiary care hospital. PATIENT: An 8-yr-old girl suffering from 50% body surface area burns and clinical sepsis in whom a double lumen subclavian venous catheter, placed 12 days earlier, could not be removed. INTERVENTION: Concomitant abduction and internal rotation of the shoulder and outward traction in the scapular plane plus backward pressure on the first rib while carefully pulling out the entrapped catheter. RESULT: Successful removal of the intact catheter, avoiding catheter disruption and embolization. CONCLUSION: Side hole of an acutely placed multilumen catheter may be entrapped at the costoclavicular angle. An anatomically-based maneuver may widen the gap between the clavicle and the first rib and enable safe removal of the catheter.